/* 
 * ---------------------------------------------------------------------------
 * OpenAES License
 * ---------------------------------------------------------------------------
 * Copyright (c) 2012, Nabil S. Al Ramli, www.nalramli.com
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *   - Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * ---------------------------------------------------------------------------
 */
static const char _NR[] = {
  0x4e,0x61,0x62,0x69,0x6c,0x20,0x53,0x2e,0x20,
  0x41,0x6c,0x20,0x52,0x61,0x6d,0x6c,0x69,0x00 };

#include <stdlib.h>
#include <stddef.h>
#include <time.h> 
#include <sys/timeb.h>
#include <string.h>

#ifdef WIN32
#include <process.h>
#endif

#include "oaes_config.h"
#include "oaes_lib.h"

#ifdef OAES_HAVE_ISAAC
#include "rand.h"
#define OAES_RAND(x) rand(x)
#else
#define OAES_RAND(x) rand()
#endif // OAES_HAVE_ISAAC

#define OAES_RKEY_LEN 4
#define OAES_COL_LEN 4
#define OAES_ROUND_BASE 7

// the block is padded
#define OAES_FLAG_PAD 0x01

#ifndef min
# define min(a,b) (((a)<(b)) ? (a) : (b))
#endif /* min */

typedef struct _oaes_key
{
  size_t data_len;
  uint8_t *data;
  size_t exp_data_len;
  uint8_t *exp_data;
  size_t num_keys;
  size_t key_base;
} oaes_key;

typedef struct _oaes_ctx
{
#ifdef OAES_HAVE_ISAAC
  randctx * rctx;
#endif // OAES_HAVE_ISAAC

#ifdef OAES_DEBUG
  oaes_step_cb step_cb;
#endif // OAES_DEBUG

  oaes_key * key;
  OAES_OPTION options;
  uint8_t iv[OAES_BLOCK_SIZE];
} oaes_ctx;

// "OAES<8-bit header version><8-bit type><16-bit options><8-bit flags><56-bit reserved>"
static uint8_t oaes_header[OAES_BLOCK_SIZE] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x4f, 0x41, 0x45, 0x53, 0x01, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};
static uint8_t oaes_gf_8[] = {
  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };

static uint8_t oaes_sub_byte_value[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
  /*1*/  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
  /*2*/  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
  /*3*/  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
  /*4*/  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
  /*5*/  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
  /*6*/  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
  /*7*/  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
  /*8*/  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
  /*9*/  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
  /*a*/  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
  /*b*/  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
  /*c*/  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
  /*d*/  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
  /*e*/  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
  /*f*/  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
};

static uint8_t oaes_inv_sub_byte_value[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
  /*1*/  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
  /*2*/  0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
  /*3*/  0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
  /*4*/  0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
  /*5*/  0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
  /*6*/  0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
  /*7*/  0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
  /*8*/  0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
  /*9*/  0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
  /*a*/  0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
  /*b*/  0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
  /*c*/  0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
  /*d*/  0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
  /*e*/  0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
  /*f*/  0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d,
};

static uint8_t oaes_gf_mul_2[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e, 0x10, 0x12, 0x14, 0x16, 0x18, 0x1a, 0x1c, 0x1e,
  /*1*/  0x20, 0x22, 0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30, 0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e,
  /*2*/  0x40, 0x42, 0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50, 0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e,
  /*3*/  0x60, 0x62, 0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70, 0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e,
  /*4*/  0x80, 0x82, 0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90, 0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e,
  /*5*/  0xa0, 0xa2, 0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0, 0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc, 0xbe,
  /*6*/  0xc0, 0xc2, 0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde,
  /*7*/  0xe0, 0xe2, 0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0, 0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc, 0xfe,
  /*8*/  0x1b, 0x19, 0x1f, 0x1d, 0x13, 0x11, 0x17, 0x15, 0x0b, 0x09, 0x0f, 0x0d, 0x03, 0x01, 0x07, 0x05,
  /*9*/  0x3b, 0x39, 0x3f, 0x3d, 0x33, 0x31, 0x37, 0x35, 0x2b, 0x29, 0x2f, 0x2d, 0x23, 0x21, 0x27, 0x25,
  /*a*/  0x5b, 0x59, 0x5f, 0x5d, 0x53, 0x51, 0x57, 0x55, 0x4b, 0x49, 0x4f, 0x4d, 0x43, 0x41, 0x47, 0x45,
  /*b*/  0x7b, 0x79, 0x7f, 0x7d, 0x73, 0x71, 0x77, 0x75, 0x6b, 0x69, 0x6f, 0x6d, 0x63, 0x61, 0x67, 0x65,
  /*c*/  0x9b, 0x99, 0x9f, 0x9d, 0x93, 0x91, 0x97, 0x95, 0x8b, 0x89, 0x8f, 0x8d, 0x83, 0x81, 0x87, 0x85,
  /*d*/  0xbb, 0xb9, 0xbf, 0xbd, 0xb3, 0xb1, 0xb7, 0xb5, 0xab, 0xa9, 0xaf, 0xad, 0xa3, 0xa1, 0xa7, 0xa5,
  /*e*/  0xdb, 0xd9, 0xdf, 0xdd, 0xd3, 0xd1, 0xd7, 0xd5, 0xcb, 0xc9, 0xcf, 0xcd, 0xc3, 0xc1, 0xc7, 0xc5,
  /*f*/  0xfb, 0xf9, 0xff, 0xfd, 0xf3, 0xf1, 0xf7, 0xf5, 0xeb, 0xe9, 0xef, 0xed, 0xe3, 0xe1, 0xe7, 0xe5,
};

static uint8_t oaes_gf_mul_3[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x03, 0x06, 0x05, 0x0c, 0x0f, 0x0a, 0x09, 0x18, 0x1b, 0x1e, 0x1d, 0x14, 0x17, 0x12, 0x11,
  /*1*/  0x30, 0x33, 0x36, 0x35, 0x3c, 0x3f, 0x3a, 0x39, 0x28, 0x2b, 0x2e, 0x2d, 0x24, 0x27, 0x22, 0x21,
  /*2*/  0x60, 0x63, 0x66, 0x65, 0x6c, 0x6f, 0x6a, 0x69, 0x78, 0x7b, 0x7e, 0x7d, 0x74, 0x77, 0x72, 0x71,
  /*3*/  0x50, 0x53, 0x56, 0x55, 0x5c, 0x5f, 0x5a, 0x59, 0x48, 0x4b, 0x4e, 0x4d, 0x44, 0x47, 0x42, 0x41,
  /*4*/  0xc0, 0xc3, 0xc6, 0xc5, 0xcc, 0xcf, 0xca, 0xc9, 0xd8, 0xdb, 0xde, 0xdd, 0xd4, 0xd7, 0xd2, 0xd1,
  /*5*/  0xf0, 0xf3, 0xf6, 0xf5, 0xfc, 0xff, 0xfa, 0xf9, 0xe8, 0xeb, 0xee, 0xed, 0xe4, 0xe7, 0xe2, 0xe1,
  /*6*/  0xa0, 0xa3, 0xa6, 0xa5, 0xac, 0xaf, 0xaa, 0xa9, 0xb8, 0xbb, 0xbe, 0xbd, 0xb4, 0xb7, 0xb2, 0xb1,
  /*7*/  0x90, 0x93, 0x96, 0x95, 0x9c, 0x9f, 0x9a, 0x99, 0x88, 0x8b, 0x8e, 0x8d, 0x84, 0x87, 0x82, 0x81,
  /*8*/  0x9b, 0x98, 0x9d, 0x9e, 0x97, 0x94, 0x91, 0x92, 0x83, 0x80, 0x85, 0x86, 0x8f, 0x8c, 0x89, 0x8a,
  /*9*/  0xab, 0xa8, 0xad, 0xae, 0xa7, 0xa4, 0xa1, 0xa2, 0xb3, 0xb0, 0xb5, 0xb6, 0xbf, 0xbc, 0xb9, 0xba,
  /*a*/  0xfb, 0xf8, 0xfd, 0xfe, 0xf7, 0xf4, 0xf1, 0xf2, 0xe3, 0xe0, 0xe5, 0xe6, 0xef, 0xec, 0xe9, 0xea,
  /*b*/  0xcb, 0xc8, 0xcd, 0xce, 0xc7, 0xc4, 0xc1, 0xc2, 0xd3, 0xd0, 0xd5, 0xd6, 0xdf, 0xdc, 0xd9, 0xda,
  /*c*/  0x5b, 0x58, 0x5d, 0x5e, 0x57, 0x54, 0x51, 0x52, 0x43, 0x40, 0x45, 0x46, 0x4f, 0x4c, 0x49, 0x4a,
  /*d*/  0x6b, 0x68, 0x6d, 0x6e, 0x67, 0x64, 0x61, 0x62, 0x73, 0x70, 0x75, 0x76, 0x7f, 0x7c, 0x79, 0x7a,
  /*e*/  0x3b, 0x38, 0x3d, 0x3e, 0x37, 0x34, 0x31, 0x32, 0x23, 0x20, 0x25, 0x26, 0x2f, 0x2c, 0x29, 0x2a,
  /*f*/  0x0b, 0x08, 0x0d, 0x0e, 0x07, 0x04, 0x01, 0x02, 0x13, 0x10, 0x15, 0x16, 0x1f, 0x1c, 0x19, 0x1a,
};

static uint8_t oaes_gf_mul_9[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f, 0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77,
  /*1*/  0x90, 0x99, 0x82, 0x8b, 0xb4, 0xbd, 0xa6, 0xaf, 0xd8, 0xd1, 0xca, 0xc3, 0xfc, 0xf5, 0xee, 0xe7,
  /*2*/  0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04, 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,
  /*3*/  0xab, 0xa2, 0xb9, 0xb0, 0x8f, 0x86, 0x9d, 0x94, 0xe3, 0xea, 0xf1, 0xf8, 0xc7, 0xce, 0xd5, 0xdc,
  /*4*/  0x76, 0x7f, 0x64, 0x6d, 0x52, 0x5b, 0x40, 0x49, 0x3e, 0x37, 0x2c, 0x25, 0x1a, 0x13, 0x08, 0x01,
  /*5*/  0xe6, 0xef, 0xf4, 0xfd, 0xc2, 0xcb, 0xd0, 0xd9, 0xae, 0xa7, 0xbc, 0xb5, 0x8a, 0x83, 0x98, 0x91,
  /*6*/  0x4d, 0x44, 0x5f, 0x56, 0x69, 0x60, 0x7b, 0x72, 0x05, 0x0c, 0x17, 0x1e, 0x21, 0x28, 0x33, 0x3a,
  /*7*/  0xdd, 0xd4, 0xcf, 0xc6, 0xf9, 0xf0, 0xeb, 0xe2, 0x95, 0x9c, 0x87, 0x8e, 0xb1, 0xb8, 0xa3, 0xaa,
  /*8*/  0xec, 0xe5, 0xfe, 0xf7, 0xc8, 0xc1, 0xda, 0xd3, 0xa4, 0xad, 0xb6, 0xbf, 0x80, 0x89, 0x92, 0x9b,
  /*9*/  0x7c, 0x75, 0x6e, 0x67, 0x58, 0x51, 0x4a, 0x43, 0x34, 0x3d, 0x26, 0x2f, 0x10, 0x19, 0x02, 0x0b,
  /*a*/  0xd7, 0xde, 0xc5, 0xcc, 0xf3, 0xfa, 0xe1, 0xe8, 0x9f, 0x96, 0x8d, 0x84, 0xbb, 0xb2, 0xa9, 0xa0,
  /*b*/  0x47, 0x4e, 0x55, 0x5c, 0x63, 0x6a, 0x71, 0x78, 0x0f, 0x06, 0x1d, 0x14, 0x2b, 0x22, 0x39, 0x30,
  /*c*/  0x9a, 0x93, 0x88, 0x81, 0xbe, 0xb7, 0xac, 0xa5, 0xd2, 0xdb, 0xc0, 0xc9, 0xf6, 0xff, 0xe4, 0xed,
  /*d*/  0x0a, 0x03, 0x18, 0x11, 0x2e, 0x27, 0x3c, 0x35, 0x42, 0x4b, 0x50, 0x59, 0x66, 0x6f, 0x74, 0x7d,
  /*e*/  0xa1, 0xa8, 0xb3, 0xba, 0x85, 0x8c, 0x97, 0x9e, 0xe9, 0xe0, 0xfb, 0xf2, 0xcd, 0xc4, 0xdf, 0xd6,
  /*f*/  0x31, 0x38, 0x23, 0x2a, 0x15, 0x1c, 0x07, 0x0e, 0x79, 0x70, 0x6b, 0x62, 0x5d, 0x54, 0x4f, 0x46,
};

static uint8_t oaes_gf_mul_b[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x0b, 0x16, 0x1d, 0x2c, 0x27, 0x3a, 0x31, 0x58, 0x53, 0x4e, 0x45, 0x74, 0x7f, 0x62, 0x69,
  /*1*/  0xb0, 0xbb, 0xa6, 0xad, 0x9c, 0x97, 0x8a, 0x81, 0xe8, 0xe3, 0xfe, 0xf5, 0xc4, 0xcf, 0xd2, 0xd9,
  /*2*/  0x7b, 0x70, 0x6d, 0x66, 0x57, 0x5c, 0x41, 0x4a, 0x23, 0x28, 0x35, 0x3e, 0x0f, 0x04, 0x19, 0x12,
  /*3*/  0xcb, 0xc0, 0xdd, 0xd6, 0xe7, 0xec, 0xf1, 0xfa, 0x93, 0x98, 0x85, 0x8e, 0xbf, 0xb4, 0xa9, 0xa2,
  /*4*/  0xf6, 0xfd, 0xe0, 0xeb, 0xda, 0xd1, 0xcc, 0xc7, 0xae, 0xa5, 0xb8, 0xb3, 0x82, 0x89, 0x94, 0x9f,
  /*5*/  0x46, 0x4d, 0x50, 0x5b, 0x6a, 0x61, 0x7c, 0x77, 0x1e, 0x15, 0x08, 0x03, 0x32, 0x39, 0x24, 0x2f,
  /*6*/  0x8d, 0x86, 0x9b, 0x90, 0xa1, 0xaa, 0xb7, 0xbc, 0xd5, 0xde, 0xc3, 0xc8, 0xf9, 0xf2, 0xef, 0xe4,
  /*7*/  0x3d, 0x36, 0x2b, 0x20, 0x11, 0x1a, 0x07, 0x0c, 0x65, 0x6e, 0x73, 0x78, 0x49, 0x42, 0x5f, 0x54,
  /*8*/  0xf7, 0xfc, 0xe1, 0xea, 0xdb, 0xd0, 0xcd, 0xc6, 0xaf, 0xa4, 0xb9, 0xb2, 0x83, 0x88, 0x95, 0x9e,
  /*9*/  0x47, 0x4c, 0x51, 0x5a, 0x6b, 0x60, 0x7d, 0x76, 0x1f, 0x14, 0x09, 0x02, 0x33, 0x38, 0x25, 0x2e,
  /*a*/  0x8c, 0x87, 0x9a, 0x91, 0xa0, 0xab, 0xb6, 0xbd, 0xd4, 0xdf, 0xc2, 0xc9, 0xf8, 0xf3, 0xee, 0xe5,
  /*b*/  0x3c, 0x37, 0x2a, 0x21, 0x10, 0x1b, 0x06, 0x0d, 0x64, 0x6f, 0x72, 0x79, 0x48, 0x43, 0x5e, 0x55,
  /*c*/  0x01, 0x0a, 0x17, 0x1c, 0x2d, 0x26, 0x3b, 0x30, 0x59, 0x52, 0x4f, 0x44, 0x75, 0x7e, 0x63, 0x68,
  /*d*/  0xb1, 0xba, 0xa7, 0xac, 0x9d, 0x96, 0x8b, 0x80, 0xe9, 0xe2, 0xff, 0xf4, 0xc5, 0xce, 0xd3, 0xd8,
  /*e*/  0x7a, 0x71, 0x6c, 0x67, 0x56, 0x5d, 0x40, 0x4b, 0x22, 0x29, 0x34, 0x3f, 0x0e, 0x05, 0x18, 0x13,
  /*f*/  0xca, 0xc1, 0xdc, 0xd7, 0xe6, 0xed, 0xf0, 0xfb, 0x92, 0x99, 0x84, 0x8f, 0xbe, 0xb5, 0xa8, 0xa3,
};

static uint8_t oaes_gf_mul_d[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x0d, 0x1a, 0x17, 0x34, 0x39, 0x2e, 0x23, 0x68, 0x65, 0x72, 0x7f, 0x5c, 0x51, 0x46, 0x4b,
  /*1*/  0xd0, 0xdd, 0xca, 0xc7, 0xe4, 0xe9, 0xfe, 0xf3, 0xb8, 0xb5, 0xa2, 0xaf, 0x8c, 0x81, 0x96, 0x9b,
  /*2*/  0xbb, 0xb6, 0xa1, 0xac, 0x8f, 0x82, 0x95, 0x98, 0xd3, 0xde, 0xc9, 0xc4, 0xe7, 0xea, 0xfd, 0xf0,
  /*3*/  0x6b, 0x66, 0x71, 0x7c, 0x5f, 0x52, 0x45, 0x48, 0x03, 0x0e, 0x19, 0x14, 0x37, 0x3a, 0x2d, 0x20,
  /*4*/  0x6d, 0x60, 0x77, 0x7a, 0x59, 0x54, 0x43, 0x4e, 0x05, 0x08, 0x1f, 0x12, 0x31, 0x3c, 0x2b, 0x26,
  /*5*/  0xbd, 0xb0, 0xa7, 0xaa, 0x89, 0x84, 0x93, 0x9e, 0xd5, 0xd8, 0xcf, 0xc2, 0xe1, 0xec, 0xfb, 0xf6,
  /*6*/  0xd6, 0xdb, 0xcc, 0xc1, 0xe2, 0xef, 0xf8, 0xf5, 0xbe, 0xb3, 0xa4, 0xa9, 0x8a, 0x87, 0x90, 0x9d,
  /*7*/  0x06, 0x0b, 0x1c, 0x11, 0x32, 0x3f, 0x28, 0x25, 0x6e, 0x63, 0x74, 0x79, 0x5a, 0x57, 0x40, 0x4d,
  /*8*/  0xda, 0xd7, 0xc0, 0xcd, 0xee, 0xe3, 0xf4, 0xf9, 0xb2, 0xbf, 0xa8, 0xa5, 0x86, 0x8b, 0x9c, 0x91,
  /*9*/  0x0a, 0x07, 0x10, 0x1d, 0x3e, 0x33, 0x24, 0x29, 0x62, 0x6f, 0x78, 0x75, 0x56, 0x5b, 0x4c, 0x41,
  /*a*/  0x61, 0x6c, 0x7b, 0x76, 0x55, 0x58, 0x4f, 0x42, 0x09, 0x04, 0x13, 0x1e, 0x3d, 0x30, 0x27, 0x2a,
  /*b*/  0xb1, 0xbc, 0xab, 0xa6, 0x85, 0x88, 0x9f, 0x92, 0xd9, 0xd4, 0xc3, 0xce, 0xed, 0xe0, 0xf7, 0xfa,
  /*c*/  0xb7, 0xba, 0xad, 0xa0, 0x83, 0x8e, 0x99, 0x94, 0xdf, 0xd2, 0xc5, 0xc8, 0xeb, 0xe6, 0xf1, 0xfc,
  /*d*/  0x67, 0x6a, 0x7d, 0x70, 0x53, 0x5e, 0x49, 0x44, 0x0f, 0x02, 0x15, 0x18, 0x3b, 0x36, 0x21, 0x2c,
  /*e*/  0x0c, 0x01, 0x16, 0x1b, 0x38, 0x35, 0x22, 0x2f, 0x64, 0x69, 0x7e, 0x73, 0x50, 0x5d, 0x4a, 0x47,
  /*f*/  0xdc, 0xd1, 0xc6, 0xcb, 0xe8, 0xe5, 0xf2, 0xff, 0xb4, 0xb9, 0xae, 0xa3, 0x80, 0x8d, 0x9a, 0x97,
};

static uint8_t oaes_gf_mul_e[16][16] = {
  //     0,    1,    2,    3,    4,    5,    6,    7,    8,    9,    a,    b,    c,    d,    e,    f,
  /*0*/  0x00, 0x0e, 0x1c, 0x12, 0x38, 0x36, 0x24, 0x2a, 0x70, 0x7e, 0x6c, 0x62, 0x48, 0x46, 0x54, 0x5a,
  /*1*/  0xe0, 0xee, 0xfc, 0xf2, 0xd8, 0xd6, 0xc4, 0xca, 0x90, 0x9e, 0x8c, 0x82, 0xa8, 0xa6, 0xb4, 0xba,
  /*2*/  0xdb, 0xd5, 0xc7, 0xc9, 0xe3, 0xed, 0xff, 0xf1, 0xab, 0xa5, 0xb7, 0xb9, 0x93, 0x9d, 0x8f, 0x81,
  /*3*/  0x3b, 0x35, 0x27, 0x29, 0x03, 0x0d, 0x1f, 0x11, 0x4b, 0x45, 0x57, 0x59, 0x73, 0x7d, 0x6f, 0x61,
  /*4*/  0xad, 0xa3, 0xb1, 0xbf, 0x95, 0x9b, 0x89, 0x87, 0xdd, 0xd3, 0xc1, 0xcf, 0xe5, 0xeb, 0xf9, 0xf7,
  /*5*/  0x4d, 0x43, 0x51, 0x5f, 0x75, 0x7b, 0x69, 0x67, 0x3d, 0x33, 0x21, 0x2f, 0x05, 0x0b, 0x19, 0x17,
  /*6*/  0x76, 0x78, 0x6a, 0x64, 0x4e, 0x40, 0x52, 0x5c, 0x06, 0x08, 0x1a, 0x14, 0x3e, 0x30, 0x22, 0x2c,
  /*7*/  0x96, 0x98, 0x8a, 0x84, 0xae, 0xa0, 0xb2, 0xbc, 0xe6, 0xe8, 0xfa, 0xf4, 0xde, 0xd0, 0xc2, 0xcc,
  /*8*/  0x41, 0x4f, 0x5d, 0x53, 0x79, 0x77, 0x65, 0x6b, 0x31, 0x3f, 0x2d, 0x23, 0x09, 0x07, 0x15, 0x1b,
  /*9*/  0xa1, 0xaf, 0xbd, 0xb3, 0x99, 0x97, 0x85, 0x8b, 0xd1, 0xdf, 0xcd, 0xc3, 0xe9, 0xe7, 0xf5, 0xfb,
  /*a*/  0x9a, 0x94, 0x86, 0x88, 0xa2, 0xac, 0xbe, 0xb0, 0xea, 0xe4, 0xf6, 0xf8, 0xd2, 0xdc, 0xce, 0xc0,
  /*b*/  0x7a, 0x74, 0x66, 0x68, 0x42, 0x4c, 0x5e, 0x50, 0x0a, 0x04, 0x16, 0x18, 0x32, 0x3c, 0x2e, 0x20,
  /*c*/  0xec, 0xe2, 0xf0, 0xfe, 0xd4, 0xda, 0xc8, 0xc6, 0x9c, 0x92, 0x80, 0x8e, 0xa4, 0xaa, 0xb8, 0xb6,
  /*d*/  0x0c, 0x02, 0x10, 0x1e, 0x34, 0x3a, 0x28, 0x26, 0x7c, 0x72, 0x60, 0x6e, 0x44, 0x4a, 0x58, 0x56,
  /*e*/  0x37, 0x39, 0x2b, 0x25, 0x0f, 0x01, 0x13, 0x1d, 0x47, 0x49, 0x5b, 0x55, 0x7f, 0x71, 0x63, 0x6d,
  /*f*/  0xd7, 0xd9, 0xcb, 0xc5, 0xef, 0xe1, 0xf3, 0xfd, 0xa7, 0xa9, 0xbb, 0xb5, 0x9f, 0x91, 0x83, 0x8d,
};

static OAES_RET oaes_sub_byte( uint8_t * byte )
{
  size_t _x, _y;
  
  if( NULL == byte )
    return OAES_RET_ARG1;

  _x = _y = *byte;
  _x &= 0x0f;
  _y &= 0xf0;
  _y >>= 4;
  *byte = oaes_sub_byte_value[_y][_x];
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_inv_sub_byte( uint8_t * byte )
{
  size_t _x, _y;
  
  if( NULL == byte )
    return OAES_RET_ARG1;

  _x = _y = *byte;
  _x &= 0x0f;
  _y &= 0xf0;
  _y >>= 4;
  *byte = oaes_inv_sub_byte_value[_y][_x];
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_word_rot_right( uint8_t word[OAES_COL_LEN] )
{
  uint8_t _temp[OAES_COL_LEN];
  
  if( NULL == word )
    return OAES_RET_ARG1;

  memcpy( _temp + 1, word, OAES_COL_LEN - 1 );
  _temp[0] = word[OAES_COL_LEN - 1];
  memcpy( word, _temp, OAES_COL_LEN );
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_word_rot_left( uint8_t word[OAES_COL_LEN] )
{
  uint8_t _temp[OAES_COL_LEN];
  
  if( NULL == word )
    return OAES_RET_ARG1;

  memcpy( _temp, word + 1, OAES_COL_LEN - 1 );
  _temp[OAES_COL_LEN - 1] = word[0];
  memcpy( word, _temp, OAES_COL_LEN );
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_shift_rows( uint8_t block[OAES_BLOCK_SIZE] )
{
  uint8_t _temp[OAES_BLOCK_SIZE];

  if( NULL == block )
    return OAES_RET_ARG1;

  _temp[0x00] = block[0x00];
  _temp[0x01] = block[0x05];
  _temp[0x02] = block[0x0a];
  _temp[0x03] = block[0x0f];
  _temp[0x04] = block[0x04];
  _temp[0x05] = block[0x09];
  _temp[0x06] = block[0x0e];
  _temp[0x07] = block[0x03];
  _temp[0x08] = block[0x08];
  _temp[0x09] = block[0x0d];
  _temp[0x0a] = block[0x02];
  _temp[0x0b] = block[0x07];
  _temp[0x0c] = block[0x0c];
  _temp[0x0d] = block[0x01];
  _temp[0x0e] = block[0x06];
  _temp[0x0f] = block[0x0b];
  memcpy( block, _temp, OAES_BLOCK_SIZE );
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_inv_shift_rows( uint8_t block[OAES_BLOCK_SIZE] )
{
  uint8_t _temp[OAES_BLOCK_SIZE];

  if( NULL == block )
    return OAES_RET_ARG1;

  _temp[0x00] = block[0x00];
  _temp[0x01] = block[0x0d];
  _temp[0x02] = block[0x0a];
  _temp[0x03] = block[0x07];
  _temp[0x04] = block[0x04];
  _temp[0x05] = block[0x01];
  _temp[0x06] = block[0x0e];
  _temp[0x07] = block[0x0b];
  _temp[0x08] = block[0x08];
  _temp[0x09] = block[0x05];
  _temp[0x0a] = block[0x02];
  _temp[0x0b] = block[0x0f];
  _temp[0x0c] = block[0x0c];
  _temp[0x0d] = block[0x09];
  _temp[0x0e] = block[0x06];
  _temp[0x0f] = block[0x03];
  memcpy( block, _temp, OAES_BLOCK_SIZE );
  
  return OAES_RET_SUCCESS;
}

static uint8_t oaes_gf_mul(uint8_t left, uint8_t right)
{
  size_t _x, _y;
  
  _x = _y = left;
  _x &= 0x0f;
  _y &= 0xf0;
  _y >>= 4;
  
  switch( right )
  {
    case 0x02:
      return oaes_gf_mul_2[_y][_x];
      break;
    case 0x03:
      return oaes_gf_mul_3[_y][_x];
      break;
    case 0x09:
      return oaes_gf_mul_9[_y][_x];
      break;
    case 0x0b:
      return oaes_gf_mul_b[_y][_x];
      break;
    case 0x0d:
      return oaes_gf_mul_d[_y][_x];
      break;
    case 0x0e:
      return oaes_gf_mul_e[_y][_x];
      break;
    default:
      return left;
      break;
  }
}

static OAES_RET oaes_mix_cols( uint8_t word[OAES_COL_LEN] )
{
  uint8_t _temp[OAES_COL_LEN];

  if( NULL == word )
    return OAES_RET_ARG1;
  
  _temp[0] = oaes_gf_mul(word[0], 0x02) ^ oaes_gf_mul( word[1], 0x03 ) ^
      word[2] ^ word[3];
  _temp[1] = word[0] ^ oaes_gf_mul( word[1], 0x02 ) ^
      oaes_gf_mul( word[2], 0x03 ) ^ word[3];
  _temp[2] = word[0] ^ word[1] ^
      oaes_gf_mul( word[2], 0x02 ) ^ oaes_gf_mul( word[3], 0x03 );
  _temp[3] = oaes_gf_mul( word[0], 0x03 ) ^ word[1] ^
      word[2] ^ oaes_gf_mul( word[3], 0x02 );
  memcpy( word, _temp, OAES_COL_LEN );
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_inv_mix_cols( uint8_t word[OAES_COL_LEN] )
{
  uint8_t _temp[OAES_COL_LEN];

  if( NULL == word )
    return OAES_RET_ARG1;
  
  _temp[0] = oaes_gf_mul( word[0], 0x0e ) ^ oaes_gf_mul( word[1], 0x0b ) ^
      oaes_gf_mul( word[2], 0x0d ) ^ oaes_gf_mul( word[3], 0x09 );
  _temp[1] = oaes_gf_mul( word[0], 0x09 ) ^ oaes_gf_mul( word[1], 0x0e ) ^
      oaes_gf_mul( word[2], 0x0b ) ^ oaes_gf_mul( word[3], 0x0d );
  _temp[2] = oaes_gf_mul( word[0], 0x0d ) ^ oaes_gf_mul( word[1], 0x09 ) ^
      oaes_gf_mul( word[2], 0x0e ) ^ oaes_gf_mul( word[3], 0x0b );
  _temp[3] = oaes_gf_mul( word[0], 0x0b ) ^ oaes_gf_mul( word[1], 0x0d ) ^
      oaes_gf_mul( word[2], 0x09 ) ^ oaes_gf_mul( word[3], 0x0e );
  memcpy( word, _temp, OAES_COL_LEN );
  
  return OAES_RET_SUCCESS;
}

OAES_RET oaes_sprintf(
    char * buf, size_t * buf_len, const uint8_t * data, size_t data_len )
{
  size_t _i, _buf_len_in;
  char _temp[4];
  
  if( NULL == buf_len )
    return OAES_RET_ARG2;

  _buf_len_in = *buf_len;
  *buf_len = data_len * 3 + data_len / OAES_BLOCK_SIZE + 1;
  
  if( NULL == buf )
    return OAES_RET_SUCCESS;

  if( *buf_len > _buf_len_in )
    return OAES_RET_BUF;

  if( NULL == data )
    return OAES_RET_ARG3;

  strcpy( buf, "" );
  
  for( _i = 0; _i < data_len; _i++ )
  {
    sprintf( _temp, "%02x ", data[_i] );
    strcat( buf, _temp );
    if( _i && 0 == ( _i + 1 ) % OAES_BLOCK_SIZE )
      strcat( buf, "\n" );
  }
  
  return OAES_RET_SUCCESS;
}

#ifdef OAES_HAVE_ISAAC
static void oaes_get_seed( char buf[RANDSIZ + 1] )
{
  struct timeb timer;
  struct tm *gmTimer;
  char * _test = NULL;
  
  ftime (&timer);
  gmTimer = gmtime( &timer.time );
  _test = (char *) calloc( sizeof( char ), timer.millitm );
  sprintf( buf, "%04d%02d%02d%02d%02d%02d%03d%p%d",
    gmTimer->tm_year + 1900, gmTimer->tm_mon + 1, gmTimer->tm_mday,
    gmTimer->tm_hour, gmTimer->tm_min, gmTimer->tm_sec, timer.millitm,
    _test + timer.millitm, getpid() );
  
  if( _test )
    free( _test );
}
#else
static uint32_t oaes_get_seed()
{
  struct timeb timer;
  struct tm *gmTimer;
  char * _test = NULL;
  uint32_t _ret = 0;
  
  ftime (&timer);
  gmTimer = gmtime( &timer.time );
  _test = (char *) calloc( sizeof( char ), timer.millitm );
  _ret = gmTimer->tm_year + 1900 + gmTimer->tm_mon + 1 + gmTimer->tm_mday +
      gmTimer->tm_hour + gmTimer->tm_min + gmTimer->tm_sec + timer.millitm +
      (uint32_t) ( _test + timer.millitm ) + getpid();

  if( _test )
    free( _test );
  
  return _ret;
}
#endif // OAES_HAVE_ISAAC

static OAES_RET oaes_key_destroy( oaes_key ** key )
{
  if( NULL == *key )
    return OAES_RET_SUCCESS;
  
  if( (*key)->data )
  {
    free( (*key)->data );
    (*key)->data = NULL;
  }
  
  if( (*key)->exp_data )
  {
    free( (*key)->exp_data );
    (*key)->exp_data = NULL;
  }
  
  (*key)->data_len = 0;
  (*key)->exp_data_len = 0;
  (*key)->num_keys = 0;
  (*key)->key_base = 0;
  free( *key );
  *key = NULL;
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_key_expand( OAES_CTX * ctx )
{
  size_t _i, _j;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == _ctx->key )
    return OAES_RET_NOKEY;
  
  _ctx->key->key_base = _ctx->key->data_len / OAES_RKEY_LEN;
  _ctx->key->num_keys =  _ctx->key->key_base + OAES_ROUND_BASE;
          
  _ctx->key->exp_data_len = _ctx->key->num_keys * OAES_RKEY_LEN * OAES_COL_LEN;
  _ctx->key->exp_data = (uint8_t *)
      calloc( _ctx->key->exp_data_len, sizeof( uint8_t ));
  
  if( NULL == _ctx->key->exp_data )
    return OAES_RET_MEM;
  
  // the first _ctx->key->data_len are a direct copy
  memcpy( _ctx->key->exp_data, _ctx->key->data, _ctx->key->data_len );

  // apply ExpandKey algorithm for remainder
  for( _i = _ctx->key->key_base; _i < _ctx->key->num_keys * OAES_RKEY_LEN; _i++ )
  {
    uint8_t _temp[OAES_COL_LEN];
    
    memcpy( _temp,
        _ctx->key->exp_data + ( _i - 1 ) * OAES_RKEY_LEN, OAES_COL_LEN );
    
    // transform key column
    if( 0 == _i % _ctx->key->key_base )
    {
      oaes_word_rot_left( _temp );

      for( _j = 0; _j < OAES_COL_LEN; _j++ )
        oaes_sub_byte( _temp + _j );

      _temp[0] = _temp[0] ^ oaes_gf_8[ _i / _ctx->key->key_base - 1 ];
    }
    else if( _ctx->key->key_base > 6 && 4 == _i % _ctx->key->key_base )
    {
      for( _j = 0; _j < OAES_COL_LEN; _j++ )
        oaes_sub_byte( _temp + _j );
    }
    
    for( _j = 0; _j < OAES_COL_LEN; _j++ )
    {
      _ctx->key->exp_data[ _i * OAES_RKEY_LEN + _j ] =
          _ctx->key->exp_data[ ( _i - _ctx->key->key_base ) *
          OAES_RKEY_LEN + _j ] ^ _temp[_j];
    }
  }
  
  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_key_gen( OAES_CTX * ctx, size_t key_size )
{
  size_t _i;
  oaes_key * _key = NULL;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  OAES_RET _rc = OAES_RET_SUCCESS;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  _key = (oaes_key *) calloc( sizeof( oaes_key ), 1 );
  
  if( NULL == _key )
    return OAES_RET_MEM;
  
  if( _ctx->key )
    oaes_key_destroy( &(_ctx->key) );
  
  _key->data_len = key_size;
  _key->data = (uint8_t *) calloc( key_size, sizeof( uint8_t ));
  
  if( NULL == _key->data )
  {
    free(_key);
    return OAES_RET_MEM;
  }

  for( _i = 0; _i < key_size; _i++ )
    _key->data[_i] = (uint8_t) OAES_RAND(_ctx->rctx);
  
  _ctx->key = _key;
  _rc = _rc || oaes_key_expand( ctx );
  
  if( _rc != OAES_RET_SUCCESS )
  {
    oaes_key_destroy( &(_ctx->key) );
    return _rc;
  }
  
  return OAES_RET_SUCCESS;
}

OAES_RET oaes_key_gen_128( OAES_CTX * ctx )
{
  return oaes_key_gen( ctx, 16 );
}

OAES_RET oaes_key_gen_192( OAES_CTX * ctx )
{
  return oaes_key_gen( ctx, 24 );
}

OAES_RET oaes_key_gen_256( OAES_CTX * ctx )
{
  return oaes_key_gen( ctx, 32 );
}

OAES_RET oaes_key_export( OAES_CTX * ctx,
    uint8_t * data, size_t * data_len )
{
  size_t _data_len_in;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == _ctx->key )
    return OAES_RET_NOKEY;
  
  if( NULL == data_len )
    return OAES_RET_ARG3;

  _data_len_in = *data_len;
  // data + header
  *data_len = _ctx->key->data_len + OAES_BLOCK_SIZE;

  if( NULL == data )
    return OAES_RET_SUCCESS;
  
  if( _data_len_in < *data_len )
    return OAES_RET_BUF;
  
  // header
  memcpy( data, oaes_header, OAES_BLOCK_SIZE );
  data[5] = 0x01;
  data[7] = _ctx->key->data_len;
  memcpy( data + OAES_BLOCK_SIZE, _ctx->key->data, _ctx->key->data_len );
  
  return OAES_RET_SUCCESS;
}

OAES_RET oaes_key_export_data( OAES_CTX * ctx,
    uint8_t * data, size_t * data_len )
{
  size_t _data_len_in;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == _ctx->key )
    return OAES_RET_NOKEY;
  
  if( NULL == data_len )
    return OAES_RET_ARG3;

  _data_len_in = *data_len;
  *data_len = _ctx->key->data_len;

  if( NULL == data )
    return OAES_RET_SUCCESS;
  
  if( _data_len_in < *data_len )
    return OAES_RET_BUF;
  
  memcpy( data, _ctx->key->data, *data_len );
  
  return OAES_RET_SUCCESS;
}

OAES_RET oaes_key_import( OAES_CTX * ctx,
    const uint8_t * data, size_t data_len )
{
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  OAES_RET _rc = OAES_RET_SUCCESS;
  int _key_length;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == data )
    return OAES_RET_ARG2;
  
  switch( data_len )
  {
    case 16 + OAES_BLOCK_SIZE:
    case 24 + OAES_BLOCK_SIZE:
    case 32 + OAES_BLOCK_SIZE:
      break;
    default:
      return OAES_RET_ARG3;
  }
  
  // header
  if( 0 != memcmp( data, oaes_header, 4 ) )
    return OAES_RET_HEADER;

  // header version
  switch( data[4] )
  {
    case 0x01:
      break;
    default:
      return OAES_RET_HEADER;
  }
  
  // header type
  switch( data[5] )
  {
    case 0x01:
      break;
    default:
      return OAES_RET_HEADER;
  }
  
  // options
  _key_length = data[7];
  switch( _key_length )
  {
    case 16:
    case 24:
    case 32:
      break;
    default:
      return OAES_RET_HEADER;
  }
  
  if( data_len != _key_length + OAES_BLOCK_SIZE )
      return OAES_RET_ARG3;
  
  if( _ctx->key )
    oaes_key_destroy( &(_ctx->key) );
  
  _ctx->key = (oaes_key *) calloc( sizeof( oaes_key ), 1 );
  
  if( NULL == _ctx->key )
    return OAES_RET_MEM;
  
  _ctx->key->data_len = _key_length;
  _ctx->key->data = (uint8_t *)
      calloc( _key_length, sizeof( uint8_t ));
  
  if( NULL == _ctx->key->data )
  {
    oaes_key_destroy( &(_ctx->key) );
    return OAES_RET_MEM;
  }

  memcpy( _ctx->key->data, data + OAES_BLOCK_SIZE, _key_length );
  _rc = _rc || oaes_key_expand( ctx );
  
  if( _rc != OAES_RET_SUCCESS )
  {
    oaes_key_destroy( &(_ctx->key) );
    return _rc;
  }
  
  return OAES_RET_SUCCESS;
}

OAES_RET oaes_key_import_data( OAES_CTX * ctx,
    const uint8_t * data, size_t data_len )
{
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  OAES_RET _rc = OAES_RET_SUCCESS;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == data )
    return OAES_RET_ARG2;
  
  switch( data_len )
  {
    case 16:
    case 24:
    case 32:
      break;
    default:
      return OAES_RET_ARG3;
  }
  
  if( _ctx->key )
    oaes_key_destroy( &(_ctx->key) );
  
  _ctx->key = (oaes_key *) calloc( sizeof( oaes_key ), 1 );
  
  if( NULL == _ctx->key )
    return OAES_RET_MEM;
  
  _ctx->key->data_len = data_len;
  _ctx->key->data = (uint8_t *)
      calloc( data_len, sizeof( uint8_t ));
  
  if( NULL == _ctx->key->data )
  {
    oaes_key_destroy( &(_ctx->key) );
    return OAES_RET_MEM;
  }

  memcpy( _ctx->key->data, data, data_len );
  _rc = _rc || oaes_key_expand( ctx );
  
  if( _rc != OAES_RET_SUCCESS )
  {
    oaes_key_destroy( &(_ctx->key) );
    return _rc;
  }
  
  return OAES_RET_SUCCESS;
}

OAES_CTX * oaes_alloc()
{
  oaes_ctx * _ctx = (oaes_ctx *) calloc( sizeof( oaes_ctx ), 1 );
  
  if( NULL == _ctx )
    return NULL;

#ifdef OAES_HAVE_ISAAC
  {
    ub4 _i = 0;
    char _seed[RANDSIZ + 1];
    
    _ctx->rctx = (randctx *) calloc( sizeof( randctx ), 1 );

    if( NULL == _ctx->rctx )
    {
      free( _ctx );
      return NULL;
    }

    oaes_get_seed( _seed );
    memset( _ctx->rctx->randrsl, 0, RANDSIZ );
    memcpy( _ctx->rctx->randrsl, _seed, RANDSIZ );
    randinit( _ctx->rctx, TRUE);
  }
#else
    srand( oaes_get_seed() );
#endif // OAES_HAVE_ISAAC

  _ctx->key = NULL;
  oaes_set_option( _ctx, OAES_OPTION_CBC, NULL );

#ifdef OAES_DEBUG
  _ctx->step_cb = NULL;
  oaes_set_option( _ctx, OAES_OPTION_STEP_OFF, NULL );
#endif // OAES_DEBUG

  return (OAES_CTX *) _ctx;
}

OAES_RET oaes_free( OAES_CTX ** ctx )
{
  oaes_ctx ** _ctx = (oaes_ctx **) ctx;

  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == *_ctx )
    return OAES_RET_SUCCESS;
  
  if( (*_ctx)->key )
    oaes_key_destroy( &((*_ctx)->key) );

#ifdef OAES_HAVE_ISAAC
  if( (*_ctx)->rctx )
  {
    free( (*_ctx)->rctx );
    (*_ctx)->rctx = NULL;
  }
#endif // OAES_HAVE_ISAAC
  
  free( *_ctx );
  *_ctx = NULL;

  return OAES_RET_SUCCESS;
}

OAES_RET oaes_set_option( OAES_CTX * ctx,
    OAES_OPTION option, const void * value )
{
  size_t _i;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;

  switch( option )
  {
    case OAES_OPTION_ECB:
      _ctx->options &= ~OAES_OPTION_CBC;
      memset( _ctx->iv, 0, OAES_BLOCK_SIZE );
      break;

    case OAES_OPTION_CBC:
      _ctx->options &= ~OAES_OPTION_ECB;
      if( value )
        memcpy( _ctx->iv, value, OAES_BLOCK_SIZE );
      else
      {
        for( _i = 0; _i < OAES_BLOCK_SIZE; _i++ )
          _ctx->iv[_i] = (uint8_t) OAES_RAND(_ctx->rctx);
      }
      break;

#ifdef OAES_DEBUG

    case OAES_OPTION_STEP_ON:
      if( value )
      {
        _ctx->options &= ~OAES_OPTION_STEP_OFF;
        _ctx->step_cb = value;
      }
      else
      {
        _ctx->options &= ~OAES_OPTION_STEP_ON;
        _ctx->options |= OAES_OPTION_STEP_OFF;
        _ctx->step_cb = NULL;
        return OAES_RET_ARG3;
      }
      break;

    case OAES_OPTION_STEP_OFF:
      _ctx->options &= ~OAES_OPTION_STEP_ON;
      _ctx->step_cb = NULL;
      break;

#endif // OAES_DEBUG

    default:
      return OAES_RET_ARG2;
  }

  _ctx->options |= option;

  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_encrypt_block(
    OAES_CTX * ctx, uint8_t * c, size_t c_len )
{
  size_t _i, _j;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == c )
    return OAES_RET_ARG2;
  
  if( c_len != OAES_BLOCK_SIZE )
    return OAES_RET_ARG3;
  
  if( NULL == _ctx->key )
    return OAES_RET_NOKEY;
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "input", 1, NULL );
#endif // OAES_DEBUG

  // AddRoundKey(State, K0)
  for( _i = 0; _i < c_len; _i++ )
    c[_i] = c[_i] ^ _ctx->key->exp_data[_i];
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data, "k_sch", 1, NULL );
    _ctx->step_cb( c, "k_add", 1, NULL );
  }
#endif // OAES_DEBUG

  // for round = 1 step 1 to Nr–1
  for( _i = 1; _i < _ctx->key->num_keys - 1; _i++ )
  {
    // SubBytes(state)
    for( _j = 0; _j < c_len; _j++ )
      oaes_sub_byte( c + _j );

#ifdef OAES_DEBUG
    if( _ctx->step_cb )
      _ctx->step_cb( c, "s_box", _i, NULL );
#endif // OAES_DEBUG

    // ShiftRows(state)
    oaes_shift_rows( c );
    
#ifdef OAES_DEBUG
    if( _ctx->step_cb )
      _ctx->step_cb( c, "s_row", _i, NULL );
#endif // OAES_DEBUG

    // MixColumns(state)
    oaes_mix_cols( c );
    oaes_mix_cols( c + 4 );
    oaes_mix_cols( c + 8 );
    oaes_mix_cols( c + 12 );
    
#ifdef OAES_DEBUG
    if( _ctx->step_cb )
      _ctx->step_cb( c, "m_col", _i, NULL );
#endif // OAES_DEBUG

    // AddRoundKey(state, w[round*Nb, (round+1)*Nb-1])
    for( _j = 0; _j < c_len; _j++ )
      c[_j] = c[_j] ^
          _ctx->key->exp_data[_i * OAES_RKEY_LEN * OAES_COL_LEN + _j];

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data + _i * OAES_RKEY_LEN * OAES_COL_LEN,
        "k_sch", _i, NULL );
    _ctx->step_cb( c, "k_add", _i, NULL );
  }
#endif // OAES_DEBUG

  }
  
  // SubBytes(state)
  for( _i = 0; _i < c_len; _i++ )
    oaes_sub_byte( c + _i );
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "s_box", _ctx->key->num_keys - 1, NULL );
#endif // OAES_DEBUG

  // ShiftRows(state)
  oaes_shift_rows( c );

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "s_row", _ctx->key->num_keys - 1, NULL );
#endif // OAES_DEBUG

  // AddRoundKey(state, w[Nr*Nb, (Nr+1)*Nb-1])
  for( _i = 0; _i < c_len; _i++ )
    c[_i] = c[_i] ^ _ctx->key->exp_data[
        ( _ctx->key->num_keys - 1 ) * OAES_RKEY_LEN * OAES_COL_LEN + _i ];

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data +
        ( _ctx->key->num_keys - 1 ) * OAES_RKEY_LEN * OAES_COL_LEN,
        "k_sch", _ctx->key->num_keys - 1, NULL );
    _ctx->step_cb( c, "output", _ctx->key->num_keys - 1, NULL );
  }
#endif // OAES_DEBUG

  return OAES_RET_SUCCESS;
}

static OAES_RET oaes_decrypt_block(
    OAES_CTX * ctx, uint8_t * c, size_t c_len )
{
  size_t _i, _j;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == c )
    return OAES_RET_ARG2;
  
  if( c_len != OAES_BLOCK_SIZE )
    return OAES_RET_ARG3;
  
  if( NULL == _ctx->key )
    return OAES_RET_NOKEY;
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "iinput", _ctx->key->num_keys - 1, NULL );
#endif // OAES_DEBUG

  // AddRoundKey(state, w[Nr*Nb, (Nr+1)*Nb-1])
  for( _i = 0; _i < c_len; _i++ )
    c[_i] = c[_i] ^ _ctx->key->exp_data[
        ( _ctx->key->num_keys - 1 ) * OAES_RKEY_LEN * OAES_COL_LEN + _i ];

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data +
        ( _ctx->key->num_keys - 1 ) * OAES_RKEY_LEN * OAES_COL_LEN,
        "ik_sch", _ctx->key->num_keys - 1, NULL );
    _ctx->step_cb( c, "ik_add", _ctx->key->num_keys - 1, NULL );
  }
#endif // OAES_DEBUG

  for( _i = _ctx->key->num_keys - 2; _i > 0; _i-- )
  {
    // InvShiftRows(state)
    oaes_inv_shift_rows( c );

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "is_row", _i, NULL );
#endif // OAES_DEBUG

    // InvSubBytes(state)
    for( _j = 0; _j < c_len; _j++ )
      oaes_inv_sub_byte( c + _j );
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "is_box", _i, NULL );
#endif // OAES_DEBUG

    // AddRoundKey(state, w[round*Nb, (round+1)*Nb-1])
    for( _j = 0; _j < c_len; _j++ )
      c[_j] = c[_j] ^
          _ctx->key->exp_data[_i * OAES_RKEY_LEN * OAES_COL_LEN + _j];
    
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data + _i * OAES_RKEY_LEN * OAES_COL_LEN,
        "ik_sch", _i, NULL );
    _ctx->step_cb( c, "ik_add", _i, NULL );
  }
#endif // OAES_DEBUG

    // InvMixColums(state)
    oaes_inv_mix_cols( c );
    oaes_inv_mix_cols( c + 4 );
    oaes_inv_mix_cols( c + 8 );
    oaes_inv_mix_cols( c + 12 );

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "im_col", _i, NULL );
#endif // OAES_DEBUG

  }

  // InvShiftRows(state)
  oaes_inv_shift_rows( c );

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "is_row", 1, NULL );
#endif // OAES_DEBUG

  // InvSubBytes(state)
  for( _i = 0; _i < c_len; _i++ )
    oaes_inv_sub_byte( c + _i );

#ifdef OAES_DEBUG
  if( _ctx->step_cb )
    _ctx->step_cb( c, "is_box", 1, NULL );
#endif // OAES_DEBUG

  // AddRoundKey(state, w[0, Nb-1])
  for( _i = 0; _i < c_len; _i++ )
    c[_i] = c[_i] ^ _ctx->key->exp_data[_i];
  
#ifdef OAES_DEBUG
  if( _ctx->step_cb )
  {
    _ctx->step_cb( _ctx->key->exp_data, "ik_sch", 1, NULL );
    _ctx->step_cb( c, "ioutput", 1, NULL );
  }
#endif // OAES_DEBUG

  return OAES_RET_SUCCESS;
}

OAES_RET oaes_encrypt( OAES_CTX * ctx,
    const uint8_t * m, size_t m_len, uint8_t * c, size_t * c_len,
    uint8_t iv[OAES_BLOCK_SIZE], uint8_t * pad )
{
  size_t _i, _j, _c_len_in;
  size_t _pad_len = m_len % OAES_BLOCK_SIZE == 0 ?
      0 : OAES_BLOCK_SIZE - m_len % OAES_BLOCK_SIZE;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  OAES_RET _rc = OAES_RET_SUCCESS;
  
  if( NULL == _ctx )
    return OAES_RET_ARG1;
  
  if( NULL == m )
    return OAES_RET_ARG2;
  
  if( NULL == c_len )
    return OAES_RET_ARG5;
  
  _c_len_in = *c_len;
  // data + pad
  *c_len = m_len + _pad_len;

  if( NULL == c )
    return OAES_RET_SUCCESS;
  
  if( _c_len_in < *c_len )
    return OAES_RET_BUF;
  
  if( NULL == iv )
    return OAES_RET_ARG6;

  if( NULL == pad )
    return OAES_RET_ARG7;

  if (NULL == _ctx->key)
    return OAES_RET_NOKEY;
  
  *pad = _pad_len ? 1 : 0;
  memcpy(c, m, m_len );
  
  for( _i = 0; _i < *c_len; _i += OAES_BLOCK_SIZE )
  {
    uint8_t _block[OAES_BLOCK_SIZE];
    size_t _block_size = min( m_len - _i, OAES_BLOCK_SIZE );

    memcpy( _block, c + _i, _block_size );
    
    // insert pad
    for( _j = 0; _j < OAES_BLOCK_SIZE - _block_size; _j++ )
      _block[ _block_size + _j ] = _j + 1;
  
    // CBC
    if( _ctx->options & OAES_OPTION_CBC )
    {
      for( _j = 0; _j < OAES_BLOCK_SIZE; _j++ )
        _block[_j] = _block[_j] ^ iv[_j];
    }

    _rc = _rc ||
        oaes_encrypt_block( ctx, _block, OAES_BLOCK_SIZE );
    memcpy( c + _i, _block, OAES_BLOCK_SIZE );
    
    if( _ctx->options & OAES_OPTION_CBC )
      memcpy( iv, _block, OAES_BLOCK_SIZE );
  }
  
  return _rc;
}

OAES_RET oaes_decrypt( OAES_CTX * ctx,
    const uint8_t * c, size_t c_len, uint8_t * m, size_t * m_len,
    uint8_t iv[OAES_BLOCK_SIZE], uint8_t pad)
{
  size_t _i, _j, _m_len_in;
  oaes_ctx * _ctx = (oaes_ctx *) ctx;
  OAES_RET _rc = OAES_RET_SUCCESS;
  uint8_t _flags;
  OAES_OPTION _options;
  
  if( NULL == ctx )
    return OAES_RET_ARG1;
  
  if( NULL == c )
    return OAES_RET_ARG2;
  
  if( c_len % OAES_BLOCK_SIZE )
    return OAES_RET_ARG3;
  
  if( NULL == m_len )
    return OAES_RET_ARG5;
  
  _m_len_in = *m_len;
  *m_len = c_len;
  
  if( NULL == m )
    return OAES_RET_SUCCESS;
  
  if( _m_len_in < *m_len )
    return OAES_RET_BUF;

  if (NULL == iv)
    return OAES_RET_ARG6;

  if (NULL == _ctx->key)
    return OAES_RET_NOKEY;
  
  // options
  _options = _ctx->options;
  // validate that all options are valid
  if( _options & ~(
        OAES_OPTION_ECB
      | OAES_OPTION_CBC
#ifdef OAES_DEBUG
      | OAES_OPTION_STEP_ON
      | OAES_OPTION_STEP_OFF
#endif // OAES_DEBUG
      ) )
    return OAES_RET_HEADER;
  if( ( _options & OAES_OPTION_ECB ) &&
      ( _options & OAES_OPTION_CBC ) )
    return OAES_RET_HEADER;
  if( _options == OAES_OPTION_NONE )
    return OAES_RET_HEADER;
  
  // data + pad
  memcpy(m, c, *m_len);
  
  for( _i = 0; _i < *m_len; _i += OAES_BLOCK_SIZE )
  {
    if( ( _options & OAES_OPTION_CBC ) && _i > 0 )
      memcpy(iv, c - OAES_BLOCK_SIZE + _i, OAES_BLOCK_SIZE);
    
    _rc = _rc ||
        oaes_decrypt_block( ctx, m + _i, min( *m_len - _i, OAES_BLOCK_SIZE ) );
    
    // CBC
    if( _options & OAES_OPTION_CBC )
    {
      for( _j = 0; _j < OAES_BLOCK_SIZE; _j++ )
        m[ _i + _j ] = m[ _i + _j ] ^ iv[_j];
    }
  }
  if( (_options & OAES_OPTION_CBC) && _i > 0 )
    memcpy(iv, c - OAES_BLOCK_SIZE + _i, OAES_BLOCK_SIZE);

  // remove pad
  if( pad )
  {
    int _is_pad = 1;
    size_t _temp = (size_t) m[*m_len - 1];

    if( _temp  <= 0x00 || _temp > 0x0f )
      return OAES_RET_HEADER;
    for( _i = 0; _i < _temp; _i++ )
      if( m[*m_len - 1 - _i] != _temp - _i )
        _is_pad = 0;
    if( _is_pad )
    {
      memset( m + *m_len - _temp, 0, _temp );
      *m_len -= _temp;
    }
    else
      return OAES_RET_HEADER;
  }
  
  return OAES_RET_SUCCESS;
}
